Peter is 180cm tall, correct to 2 significant figures. Alice is 150cm tall, correct to 2 significant figures. What is the upper and lower bound of the difference in their heights?

Upper bound of Peter's height = 185cmLower bound of Peter's height = 175cmUpper bound of Alice's height = 155cmLower bound of Alice's height = 145cmFor the upper bound of the difference, we want the upper bound of Peter's height and the lower bound of Alice's (as this gives us the biggest difference between them). 185 - 145= 40cm.For the lower bound of the difference, we want the lower bound of Peter's height and the upper bound of Alice's (as this gives us the smallest difference between them). 175 - 155= 20cm.